Bug 1325351 part 1 - Remove workaround for VC in Maybe. r=froydnj

MozReview-Commit-ID: Anlrf3D2WtN

--HG--
extra : rebase_source : 9cc2e29e374753ad40774ebd0a0efce9f9449e3b

js/public/Proxy.h

@@ -593,6 +593,15 @@ class JS_FRIEND_API(AutoEnterPolicy)
     inline void recordLeave() {}
 #endif
 
+  private:
+    // This operator needs to be deleted explicitly, otherwise Visual C++ will
+    // create it automatically when it is part of the export JS API. In that
+    // case, compile would fail because HandleId is not allowed to be assigned
+    // and consequently instantiation of assign operator of mozilla::Maybe
+    // would fail. See bug 1325351 comment 16. Copy constructor is removed at
+    // the same time for consistency.
+    AutoEnterPolicy(const AutoEnterPolicy&) = delete;
+    AutoEnterPolicy& operator=(const AutoEnterPolicy&) = delete;
 };
 
 #ifdef JS_DEBUG

mfbt/Maybe.h

@@ -157,13 +157,7 @@ public:
     if (&aOther != this) {
       if (aOther.mIsSome) {
         if (mIsSome) {
-          // XXX(seth): The correct code for this branch, below, can't be used
-          // due to a bug in Visual Studio 2010. See bug 1052940.
-          /*
           ref() = aOther.ref();
-          */
-          reset();
-          emplace(*aOther);
         } else {
           emplace(*aOther);
         }